A variety of valves are used to control flow of actuating fluids in many well applications and other flow control applications. For example, valves are employed in wellbore drilling applications to control the actuation of tools located in the wellbore being drilled. During wellbore drilling operations, valves positioned in a drilling assembly can be selectively actuated to control the direction of drilling. The valves may be positioned, for example, to control the flow of drilling mud to actuating pads which are extended and contracted in a controlled manner to steer the drill bit and thereby drill the wellbore in a desired direction.
In some drilling applications, bi-stable valves may be used to control the flow of drilling mud in both charging the actuating pads and in relieving backflow pressure. However, many types of bi-stable valves provide limited steering capacity because they exhibit no or limited dumping functionality, thus limiting backflow from the actuating pad discharge lines at high drilling RPMs. Some bi-stable valves systems are designed to perform both actuation of the actuating pads and discharge/dumping of the fluid and pressure following actuation. However, these types of bi-stable valves systems can suffer from excessive internal pressure differentials. Additionally, single-stage, bi-stable valve systems often require substantial increases in power to operate such systems under higher pressures. Existing systems also can suffer from decreasing efficiency at high drilling RPMs.